Binding in atomic nuclei reflects all the nucleonic interactions in the nucleus. These interactions determine the average nuclear potential and the residual interactions that give rise to correlated behavior in nuclei. Therefore the study of nuclear binding energies can shed light on those interactions and on the emergence of coherence and collectivity in nuclei. This will be discussed in the context of two-neutron separation energies and the specific relation of masses to shell and collective structure. Various additive functions of binding energies can be used to isolate specific interactions that play important roles in the evolution of structure. In particular, one of the main drivers of structural evolution is the proton-neutron interaction among the valence nucleons. A specific double difference of binding energies gives empirical measures of this interaction. These data highlight shell structure and the development of collectivity and deformation. In this paper, we will outline some of these ideas and touch on a few recent developments, including new insights into the roles of specific nucleon orbits. The take-away message is the deep link between nuclear structure and binding and the need to take both spectroscopic and binding energy data into account in attempting to understand atomic nuclei. (C) 2013 Elsevier B.V. All rights reserved.